JP5027119B2 - Intraocular lens - Google Patents

Description

  The present invention relates to an intraocular lens suitable for wearing in a human eye.

  Intraocular lenses are well known in ophthalmology. For example, an intraocular lens is implanted when the originally clear lens becomes turbid (cataract).

  Hyperopia associated with aging (presbyopia) is a problem inherent in ophthalmology. For example, the article “Intraocular lens”, “Ophthalmoscope” magazine, July / August 2002 issue, p. See 28-34. If the elasticity of the natural lens is lost due to aging, the refractive power cannot be adjusted, and the eye cannot be adjusted for an object at a short distance in front of the eye, so the image is clearly displayed on the retina. No image is formed. The loss of accommodation can be corrected with reading glasses, but with known costs and inconvenience.

  Various attempts have been made in the prior art to solve the problem of presbyopia.

  For example, there has been an attempt to displace an intraocular lens (IOL) by the movement of the ciliary muscles of the eye (see the above paper in “Der Augenspiegel”). However, the displacement of the IOL in the direction of the axis (conventionally referred to as the z-axis) achieved thereby is insufficient, and therefore the displacement of the focal point is insufficient.

  There have been attempts to mechanically deform the attached IOL with ciliary muscles, but no convincing results have yet been demonstrated.

  Another approach is an attempt to restore the elasticity of the natural lens by radially incising the lens using a non-invasive FS laser. 0. Kermani, “Science and Research News”, J.M. Refract Surgery Publication: 2004: No. 20, P.I. See 651-658. However, there is little change in elasticity and there is a risk of causing cataracts.

  In addition, multifocal IOL implantation has also been performed, but this involves known difficulties. In particular, confounding double images and lack of sharpness can be mentioned because there are at least two focal lengths, each with different imaging properties, resulting in two images simultaneously on the retina. It depends. “New multifocal lenses, individual solutions and post-surgery functions”, “Ophthalmoscope” magazine, September 2002, p. See 42-47.

  Another attempt to reduce presbyopia is to create a monocular field of view by laser refractive surgery on the cornea. In this example, one eye is corrected to the near point and the other eye remains adjusted to the far point, or the latter is then corrected to usually become so-called efficacy. However, in this case, since the information transmitted from the two eyes is different, the information is processed by the brain and needs to be understood by the patient.

  The present invention employs another method to restore the accommodation ability of the human eye.

  For this purpose, the present invention provides an intraocular lens whose refractive power can be changed by applying a voltage. Therefore, the present invention relates to an artificial intraocular lens that is suitable for mounting in a human eyeball, can change its refractive power by voltage or electric field, and is configured to restore the accommodation ability of the eye.

  In other applications, so-called liquid lenses have been known for some time. In this type of lens, the focal length is changed by causing a shape change of the liquid lens by applying a voltage. The underlying physical effect is also referred to as “electrowetting”. In this case, the term “liquid lens” also includes other deformable materials, in particular liquid materials. Realizing a very high dynamic range, i.e. rapid lens shape, by properly configuring the electrodes, choosing the viscosity and concentration of the lens material, taking the lens to the proper dimensions and ensuring the stability of the lens position Change is possible. For example, a range of about 2 kHz is already possible at the present time as the focal length switching frequency. Liquid lenses can be actuated by voltage and can be manufactured with diameters ranging from 3 to 6 mm. For prior art in this regard, refer to the following publications:

Kuiper, S .; Hendriks BHW, “Variable-focus Liquid Lens for Miniature Cameras”, Appl Phys Lett, 2004, 85, p. 1128-1130,
Hecht E.M. “Optics-Second Edition”, Addison Wesley Publishing Co., Chapter 5, “Geometrical Optics-Paraxial Theory”, p. 138,
Krupenkin, T .; Yang S .; Mach P .; "Adjustable liquid microlenses", Appl Phys Lett, 2003 82, p. 316-318, and Berge B. , Peseux J .; "Variable focal controlled an extra voltage: An application of electrifying", Eur Phys J, 2000 E3, p. 159-163.

  The intraocular liquid lens according to the present invention is sized and configured to be mounted within the lens capsule of the eye. The intraocular liquid lens can also be sized and configured to fit into the groove.

  The IOL that can be used in this way further comprises means that can change the mechanical surface tension of the lens by applying a voltage in order to change its focal length.

  According to a preferred configuration, the lens is dimensioned and the voltage applying means is configured so that the spherical deformation of the lens is caused by the voltage. Thus, radial symmetry is provided to the lens. Lens dimensions and configurations may be provided such that astigmatism and aberrations, particularly spherical aberrations, ie higher order eye abnormalities, are corrected by voltage.

  So-called “electrowetting” changes the surface tension of a liquid or liquid or other suitable material. The lens is configured to change its shape and / or exposed to external forces from a state when no voltage is applied, or from a state where other voltages are applied, due to a change in surface tension.

  According to a particular configuration of the IOL according to the invention, the IOL may be wholly or partly covered with a membrane and optionally provided with additional fixing elements as known in conventional intraocular lenses. A fixation element may be provided on the lens so that the lens is positioned in the eye in the desired manner.

  The shape of the IOL according to the present invention in the capsular bag in the non-voltage state can be shaped in a desired manner by the introduction of an auxiliary hydrophobic surface and the accompanying change in surface tension.

  According to a particular configuration of the invention, the intraocular lens is provided with an electrode for applying the voltage. In this case, these electrodes are at least partially transparent. Also, according to a preferred configuration of the present invention, these electrodes are arranged at an appropriate distance interval over substantially the entire circumference of the IOL.

  The voltage required to control the IOL according to the present invention can be sourced and used in various ways. For example, it is possible to use microelectronic components. Such parts are already embedded in the human eye today. H. G. Sachs and V.M. P. Gabel's co-authored paper, “Grafe's Arch. Clin. Exp. Ophthalmol.”, 2004, volume 242, p. 717-723, p. Walter, “The Vision Compensator Transplant for Progressive Retinal Dystrophy”, P.M. By Walter, “Ophthalmoscope”, November 2004, P.M. 32, T.M. Laube, C.I. Blockmann, R.M. Buss, C.I. Lau, K .; Hock, N.M. Stawski, T .; Stieglitz, H .; A. Richter, and H.C. Schilling co-authored paper, Graefe's Arch. Clin. Exp. Ophthalmol. ), 2004, volume 242, p. 661-667, and T.W. Stieglitz, R.A. Keller, H .; Beutel, and J.A. U. See Meyer, "Microsystem Integration Techniques for Intravascular Vision Procedures Using Flexible Polyimides".

  On the other hand, a physiological voltage can be provided. For example, the voltage required for accommodation can be derived directly from eye movement. In particular, it is obtained by voltage generation by triboelectricity, that is, voltage generation by friction effect. The surface curvature can be adjusted by amplifying this voltage to the required degree with the help of an embedded microchip and applying it to the electrode of a suitably configured lens. For example, the natural accommodation process requires ciliary muscle movement. In young and fully functioning eyes, ciliary muscles cause lens deformation and accommodation. One particular configuration of the present invention derives a voltage from this movement of the ciliary muscle, amplifies it sufficiently if necessary, and then applies it to the electrode of the lens to restore the natural movement of the ciliary muscle. Accordingly, a means for realizing the desired perspective adjustment is provided.

  With a specific configuration of the present invention, higher-order imaging defects and astigmatic imaging abnormalities can be solved. See EP 1 091 758 B1 and US Pat. No. 6,369,954 B1.

  Embodiments of the invention are described in more detail below with the aid of the drawings.

  In principle, the change in the refractive power or focal length of a lens can be expressed by a simple lens equation, and the lens's radius of curvature determines the focal length of the lens (see, for example, the text book by E. Hecht above). See

1 / f = (n−1) · (1 / R ₁ −1 / R ₂ ) (1)
R _1- radius of curvature of lens surface
n-Refractive Index When an intraocular lens (IOL) according to the present invention is mounted in a suitably prepared eye lens capsule, the center of the lens is basically aligned with the optical path of the eye. It is also possible to provide an additional fixing element to surround the liquid lens with a suitable membrane and to keep its central position on the optical axis of the eye. This technique itself is known from conventional IOLs.

  The change in the refractive power D of the liquid lens can be described by the following equation.

D = D ₀ + K (U ² / d) (2)
K = material constant
d = lens diameter
U = Voltage Accordingly, the change in the refractive power of the liquid lens depends in principle on the square of the applied voltage and is inversely proportional to the diameter of the lens. When the lens diameter is small and an appropriate dielectric insulating layer is present as in this case, the refractive power can be changed greatly by a relatively low voltage (see the above-mentioned paper by T. Krupenkin et al.).

  In the human eye, the lens performs accommodation ranging from about 10 dpt to about 14 dpt depending on age.

  If currently available electro-optic constants are assumed for this liquid lens material (see above work by S. Kuiper et al. And T. Krupenkin et al.), Such a change in refractive power is now known in the art. It can already be realized with a voltage in the range of U = 20-30V using the material.

  FIG. 1 shows an intraocular lens 10 mounted in a lens capsule 12 of a human eye. The iris 14 of the eye, the cornea 16 and the anterior chamber 18 are also represented.

  The intraocular lens 10 is made of the above kind of liquid material and is surrounded by an insulating liquid 20.

  According to this figure, the electrodes 22a, 22b, 22c, 22d, 22e, 22f are arranged either around the lens capsule 12 (FIGS. 1 and 2) or inside the lens capsule (FIG. 3). These electrodes can also be placed on the equatorial plane of the capsular bag. On the other hand, a fully encapsulated intraocular lens with built-in electrodes may be used.

  The natural ciliary muscle 24 engages on the lens capsule at right angles to the optical axis of the “eye” system.

Figure 1 is a state of not being accommodation, namely state voltage corresponding to D = D ₀ in the above equation has not been applied to the electrode (2), the intraocular lens 20 of the schematically. The tensile or compressive force F acting perpendicular to the optical axis is also equal to zero, ie F = 0.

FIG. 2 shows a state in which the voltage U is applied to the electrode 22, that is, a state corresponding to D = D ₀ + KU ² . The intraocular lens undergoes electrostriction contraction (perspective adjustment), and a non-zero force acts at right angles to the optical axis. That is, the desired change in shape is caused so that the radius of curvature of the 10 interface of the lens changes greatly and the refractive power increases.

  FIG. 3 shows a modified embodiment in which the system comprises a microchip 26. This embodiment is also shown in FIG. In these figures, parts that are functionally equivalent to each other or that are functionally similar are given the same reference numerals.

  In the embodiment according to FIG. 3, voltage generation by triboelectricity is used. As noted above, the natural accommodation process involves forces, such as the forces that the natural ciliary muscle exerts on the natural lens. In the embodiment according to FIG. 3, the voltage is derived from the action of this force and is sufficiently amplified before the electrodes 22a,. . , 22f, the deformation of the interface is accordingly caused to adjust the perspective.

  The generation of voltage by triboelectricity can be explained by the same method as the piezoelectric effect. However, in the former case, the charge is generated by force, whereas in the latter case, the movement starting force and charge separation are used. Benz W. , Heinks P .; , Stark L. Co-authored, “List of Electronics for Electronics Engineers in Industrial and Communication Fields”, published by Kohl + Noltmeyer, p. See 87. The following formula applies:

Δe / e to e ₁₂ (F ₁₂ / A) (3)
e ₁₂ -Elastic modulus
Δe / e-relative change in length
F ₁₂ -Component force
A-Area U = Q / C = (1 / C) S ₁₂ F ₁₂ (4)
S ₁₂ -Piezoelectric constant
C—Capacitance The voltage generated by this triboelectricity is amplified via the embedded microchip 26. The chip includes individual electrodes 22a,... Via a plurality of lines (not shown). . , 22f and control these electrodes to achieve the desired perspective adjustment.

1 schematically shows a cross section of an eye in which an intraocular lens according to the present invention is incorporated and the intraocular lens is not adjusted in perspective. It is a figure corresponding to FIG. 1, and shows the state in which the lens was adjusted. To illustrate the mode of operation, a different configuration of the IOL with a voltage control microchip is shown in the eye.

Claims (4)

Electrodes (22a, 22b, 22c, 22d, 22e, 22f) for applying a voltage to the intraocular lens (10) in order to change the surface tension of the intraocular lens (10) and its shape;
The intraocular lens (10) is configured to be mounted in the lens capsule or groove of the eye,
The electrodes are arranged around or inside the intraocular lens (10) ,
When the voltage is applied to the electrode, the surface tension is changed to cause deformation of the intraocular lens (10), and corrects astigmatism or one or more higher order aberrations (10). . "   The intraocular lens according to claim 1, wherein the intraocular lens is covered with a film.   The intraocular lens according to claim 1, comprising an anchoring element for positioning within the eye.   The intraocular lens according to claim 1, comprising a microchip (26) for triboelectric voltage processing and amplification.

Images